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Abstract:

A grill and a burner assembly therefor. The burner assembly utilizes a
V-shaped firebox having a V-shaped combustion chamber containment wall,
which defines a combustion chamber of significantly reduced volume. The
burner assembly can also have a V-shaped outer insulating wall which is
positioned outside of the combustion chamber containment wall such that
an insulating gap is formed between the inner V-shaped wall and the outer
V-shaped wall. A burner element preferably extends longitudinally within
the combustion chamber of the firebox above the bottom of the V-shaped
combustion chamber containment wall.

Claims:

1. A burner assembly for a grill comprising: (a) a firebox comprising a
longitudinally extending combustion chamber containment wall which
defines a combustion chamber therein, said combustion chamber containment
wall having a substantially V-shaped cross-section, said combustion
chamber containment wall having an upper discharge opening, and said
combustion chamber containment wall further comprising: a longitudinally
extending bottom, a longitudinally extending left side, and a
longitudinally extending right side, wherein, as viewed in said
substantially V-shaped cross-section of said combustion chamber
containment wall, said left and said right sides extend upwardly from
said bottom of said combustion chamber containment wall to said upper
discharge opening, said left and said right sides also diverge outwardly
from, or proximately from, said bottom of said combustion chamber
containment wall to, or proximately to, said upper discharge opening of
said combustion chamber containment wall, and said left and said right
sides have lower ends at said bottom of said combustion chamber
containment wall which are in close proximity to each other or are
located substantially at a shared point and (b) a burner element
extending longitudinally in said combustion chamber above said
longitudinally extending bottom of said combustion chamber containment
wall, said burner element having one or more discharge ports for
delivering a fuel or a fuel air mixture into said combustion chamber.

2. The burner assembly of claim 1 wherein: said combustion chamber
containment wall has one or more air openings through and extending along
said longitudinally extending bottom of said combustion chamber
containment wall; said burner element comprises a burner element conduit
extending longitudinally above said one or more air openings formed
through said longitudinally extending bottom of said combustion chamber
containment wall; and said one or more discharge ports in said burner
element for delivering said fuel or said fuel and air mixture into said
combustion chamber are formed through a longitudinally extending top of
said burner element conduit.

3. The burner assembly of claim 2 wherein: said combustion chamber
containment wall is substantially symmetrical with respect to a central
vertical plane extending longitudinally through said firebox; said one or
more air openings through and extending along said longitudinally
extending bottom of said combustion chamber containment wall are
substantially in alignment with said central vertical plane; and said one
or more discharge ports formed through said longitudinally extending top
of said burner element conduit are substantially in alignment with said
central vertical plane.

4. The burner assembly of claim 3 wherein, in said substantially V-shaped
cross-section of said combination chamber containment wall, said lower
ends of said left and said right sides of said combustion chamber
containment wall are located not more than 1/4 inch apart at said
longitudinally extending bottom of said combustion chamber containment
wall or are located substantially at a shared point.

5. The burner assembly of claim 4 wherein, in said substantially V-shaped
cross-section of said combustion chamber containment wall, said
longitudinally extending bottom of said combustion chamber containment
wall is substantially a vertex point shared by said lower ends of said
left and said right sides of said combustion chamber containment wall.

6. The burner assembly of claim 4 wherein said burner element conduit is
a length of NPS 1/2 inch pipe.

7. The burner assembly of claim 4 wherein said left and said right sides
of said combustion chamber containment wall are substantially straight as
viewed in said substantially V-shaped cross-section.

8. The burner assembly of claim 4 wherein said substantially V-shaped
cross-section of said combustion chamber containment wall is a birdwing
shape.

9. The burner assembly of claim 1 wherein: said combustion chamber has a
total receiving volume into which combustion gases produced by said
burner element will enter; said combustion chamber has a depth; said
upper discharge opening of said combustion chamber containment wall has a
width and a total discharge opening area; and said total receiving volume
of said combustion chamber is not more than 60% of that of a rectangular
firebox having an identical depth, an identical discharge area, and an
identical discharge opening width.

10. The burner assembly of claim 9 wherein said total receiving volume of
said combustion chamber is not more than 55% of that of said rectangular
firebox having an identical depth, an identical discharge opening area,
and an identical discharge opening width.

11. The burner assembly of claim 9 wherein said total receiving volume of
said combustion chamber is less than 50% of that of said rectangular
firebox having an identical depth, an identical discharge opening area,
and an identical discharge opening width.

12. The burner assembly of claim 1 wherein: said firebox further
comprises a longitudinally extending insulating wall positioned outside
of said combustion chamber containment wall, said insulating wall having
a substantially V-shaped cross-section and said insulating wall further
comprising: a longitudinally extending bottom, a longitudinally extending
left side, and a longitudinally extending right side, wherein, as viewed
in said substantially V-shaped cross-section of said insulating wall:
said bottom of said insulating wall is positioned below said bottom of
said combustion chamber containment wall, said left and said right sides
of said insulating wall extend upwardly from, and diverge outwardly from,
or proximately from, said bottom of said insulating wall such that (i)
said left side of said insulating wall is positioned outside of and
adjacent to said left side of said combustion chamber containment wall
such that a left side insulating gap is formed between said left sides
and (ii) said right side of said insulating wall is positioned outside of
and adjacent to said right side of said combustion chamber containment
wall such that a right side insulating gap is formed between said right
sides, and said left and said right sides of said insulating wall have
lower ends at said bottom of said insulating wall which are within one
inch of each other or less, or are located substantially at a shared
point.

13. The burner assembly of claim 12 wherein said insulating wall is
substantially parallel to said combustion chamber containment wall.

14. The burner assembly of claim 12 wherein: in said substantially
V-shaped cross-section of said combustion chamber containment wall, said
lower ends of said left and said right sides of said combustion chamber
containment wall are located not more than 1/4 inch apart at said bottom
of said combustion chamber containment wall or are located substantially
at a shared point and in said substantially V-shaped cross-section of
said insulating wall, said lower ends of said left and said right sides
of said insulating wall are located not more than 1/2 inch apart at said
bottom of said insulating wall or are located substantially at a shared
point.

15. The burner assembly of claim 14 wherein said left and said right
sides of said combustion chamber containment wall extend upwardly and
diverge outwardly from said bottom of said combustion chamber containment
wall to said upper discharge opening and said left and said right sides
of said insulating wall extend upwardly and diverge outwardly from said
bottom said insulating wall.

16. The burner assembly of claim 14 wherein said left and said right
insulating gaps are from about 0.2 to about 0.6 inch in width.

17. The burner assembly of claim 16 wherein said left and said right
insulating gaps extend substantially to said upper discharge opening of
said combustion chamber containment wall.

18. The burner assembly of claim 12 wherein said firebox is constructed
such that combustion gases produced in said combustion chamber will not
enter said left side and said right side insulating gaps.

19. The burner assembly of claim 12 wherein: said insulating wall of said
firebox has one or more air openings through said longitudinally
extending bottom of said insulating wall; said combustion chamber
containment wall of said firebox has one or more air openings through
said longitudinally extending bottom of said combustion chamber
containment wall; and said one or more air openings through said
longitudinally extending bottom of said combustion chamber containment
wall are in fluid communication with said one or more air openings
through said longitudinally extending bottom of said insulating wall.

20. The burner assembly of claim 19 wherein: said burner element
comprises a conduit extending longitudinally above said one or more air
openings formed through said longitudinally extending bottom of said
combustion chamber containment wall and above said one or more air
openings formed through said longitudinally extending bottom of said
insulating wall and said one or more discharge ports in said burner
element for delivering said fuel or said fuel and air mixture into said
combustion chamber are formed through a longitudinally extending top of
said conduit.

21. The burner assembly of claim 20 wherein: said combustion chamber
containment wall and said insulating wall are substantially symmetrical
with respect to a central vertical plane extending longitudinally through
said firebox; said one or more air openings through and extending along
said longitudinally extending bottom of said combustion chamber
containment wall are substantially in alignment with said central
vertical plane; said one or more air openings through and extending along
said longitudinally extending bottom of said insulating wall are
substantially in alignment with said central vertical plane; and said one
or more discharge parts formed through said longitudinally extending top
of said burner element conduit are substantially in alignment with said
central vertical plane.

22. The burner assembly of claim 12 wherein: in said V-shaped
cross-section of said combustion chamber containment wall, said bottom of
said combustion chamber containment wall is substantially a vertex point
shared by said lower ends of said left and said right sides of said
combustion chamber containment wall and in said V-shaped cross-section of
said insulating wall, said bottom of said insulating wall is
substantially a vertex point shared by said lower ends of said left and
said right sides of said insulating wall.

23. The burner assembly of claim 22 wherein: said left and said right
sides of said combustion chamber containment wall are substantially
straight in said V-shaped cross-section of said combustion chamber
containment wall and said left and said right sides of said insulating
wall are substantially straight in said V-shaped cross-section of said
insulating wall.

24. The burner assembly of claim 12 wherein: said left and said right
sides of said combustion chamber containment wall are curved in said
V-shaped cross-section of said combustion chamber containment wall and
said left and said right sides of said insulating wall are curved in said
V-shaped cross-section of said insulating wall.

25. The burner assembly of claim 24 wherein said V-shaped cross-sections
of said combustion chamber containment wall and said insulating wall are
birdwing shapes.

26. The burner assembly of claim 12 wherein said firebox further
comprises a flame tamer shield in said combustion chamber containment
wall above said burner element.

27. The burner assembly of claim 12 wherein said burner element is
configured and positioned, and said V-shaped cross-sections of said
combustion chamber containment wall and said insulating wall are
configured in a manner such that, when an infrared cooking grate having a
total open area of 5% is positioned on said upper discharge opening of
said combustion chamber containment wall and a grill lid over said burner
assembly is closed, said burner assembly will operate at a thermal
efficiency of at least 57% to provide a total energy flux of at least 9.4
KW/m2 in a cooking zone over said infrared cooking grate wherein at
least 72% of said total energy flux is infrared radiant energy.

28. The burner assembly of claim 12 wherein said burner element is
configured and positioned, and said V-shaped cross-sections of said
combustion chamber containment wall and said insulating wall are
configured in a manner such that, when a convective cooking grate having
a total open area of 20% is positioned on said upper discharge opening of
said combustion chamber containment wall and a grill lid over said burner
assembly is closed, said burner assembly will operate at a thermal
efficiency of at least 57% to provide a total energy flux of at least 9.4
KW/m2 in a cooking zone over said convective cooking grate with at
least 62% of said total energy flux being infrared radiant energy.

29. The burner assembly of claim 12 wherein: said firebox of said burner
assembly has a total receiving volume into which combustion gases
produced by said burner element will enter; said combustion chamber has a
depth; said upper discharge opening of said combustion chamber
containment wall has a width and a total discharge opening area; and said
total receiving volume of said firebox of said burner assembly is not
more than 60% of that of a rectangular firebox having and an identical
depth, an identical discharge opening area, and an identical discharge
opening width.

30. The burner assembly of claim 29 wherein said total receiving volume
of said firebox of said burner assembly is less than 55% of that of said
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

31. The burner of claim 29 wherein said total receiving volume of said
firebox of said burner assembly is less than 52% of that of said
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

32. The burner assembly of claim 29 wherein said total receiving volume
of said firebox of said burner assembly is less than 50% of that of said
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

33. A grill comprising: a housing and a plurality of substantially
parallel adjacent burner assemblies in said housing wherein each of said
burner assemblies comprises: (a) a firebox comprising a longitudinally
extending combustion chamber containment wall which defines a combustion
chamber therein, said combustion chamber containment wall having a
substantially V-shaped cross-section, said combustion chamber containment
wall having an upper discharge opening, and said combustion chamber
containment wall further comprising: a longitudinally extending bottom, a
longitudinally extending left side, and a longitudinally extending right
side, wherein, as viewed in said substantially V-shaped cross-section of
said combustion chamber containment wall, said left and said right sides
extend upwardly from said bottom of said combustion chamber containment
wall to said upper discharge opening, said left and said right sides also
diverge outwardly from, or proximately from, said bottom of said
combustion chamber containment wall to, or proximately to, said upper
discharge opening of said combustion chamber containment wall, and said
left and said right sides have lower ends at said bottom of said
combustion chamber containment wall which are in close proximity to each
other or are located substantially at a shared point and (b) a burner
element extending longitudinally in said combustion chamber above said
longitudinally extending bottom of said combustion chamber containment
wall, said burner element having one or more discharge ports for
delivering a fuel or a fuel air mixture into said combustion chamber.

34. The grill of claim 33 wherein said firebox further comprises a
longitudinally extending insulating wall positioned outside of said
combustion chamber containment wall, said insulating wall having a
substantially V-shaped cross-section and said insulating wall further
comprising: a longitudinally extending bottom, a longitudinally extending
left side, and a longitudinally extending right side, wherein, as viewed
in said substantially V-shaped cross-section of said insulating wall:
said bottom of said insulating wall is positioned below said bottom of
said combustion chamber containment wall, said left and said right sides
of said insulating wall extend upwardly from, and diverge outwardly from
or proximately from, said bottom of said insulating wall such that (i)
said left side of said insulating wall is positioned outside of and
adjacent to said left side of said combustion chamber containment wall
such that a left side insulating gap is formed between said left sides
and (ii) said right side of said insulating wall is positioned outside of
and adjacent to said right side of said combustion chamber containment
wall such that a right side insulating gap is formed between said right
sides, and said left and said right sides of said insulating wall have
lower ends at said bottom of said insulating wall which are in close
proximity to each other or are located substantially at a shared point.

35. The grill of claim 33 wherein: said combustion chamber containment
wall has one or more air openings through and extending along said
longitudinally extending bottom of said combustion chamber containment
wall; said burner element comprises a burner element conduit extending
longitudinally above said one or more air openings formed through said
longitudinally extending bottom of said combustion chamber containment
wall; and said one or more discharge ports in said burner element for
delivering said fuel or said fuel and air mixture into said combustion
chamber are formed through a longitudinally extending top of said burner
element conduit.

36. The grill of claim 35 wherein: said combustion chamber containment
wall is substantially symmetrical with respect to a central vertical
plane extending longitudinally through said firebox; said one or more air
openings through and extending along said longitudinally extending bottom
of said combustion chamber containment wall are substantially in
alignment with said central vertical plane; and said one or more
discharge ports formed through said longitudinally extending top of said
burner element conduit are substantially in alignment with said central
vertical plane.

37. The grill of claim 33 wherein, in said substantially V-shaped
cross-section of said combustion chamber containment wall, said
longitudinally extending bottom of said combustion chamber containment
wall is substantially a vertex point shared by said lower ends of said
left and said right sides of said combustion chamber containment wall.

38. The grill of claim 33 wherein said substantially V-shaped
cross-section of said combustion chamber containment wall is a birdwing
shape.

39. The grill of claim 33 wherein: said firebox of said burner assembly
has a total receiving volume into which combustion gases produced by said
burner element will enter; said combustion chamber has a depth; said
upper discharge opening of said combustion chamber containment wall has a
width and a total discharge opening area; and said total receiving volume
of said firebox of said burner assembly is not more than 60% of that of a
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

40. The grill of claim 39 wherein said total receiving volume of said
firebox of said burner assembly is less than 55% of that of said
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

41. The grill of claim 39 wherein said total receiving volume of said
firebox of said burner assembly is less than 52% of that of said
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

42. The grill of claim 39 wherein said total receiving volume of said
firebox of said burner assembly is less than 50% of that of said
rectangular firebox having an identical depth, an identical discharge
opening area, and an identical discharge opening width.

43. The grill of claim 33 wherein said grill further comprises a lid and
an infrared cooking grate having a total open area of 5% and wherein for
each of said burner assemblies, said burner element is configured and
positioned, and said firebox and said V-shaped cross-section of said
combustion chamber containment wall are configured in a manner such that,
when said infrared cooking grate is positioned over said upper discharge
opening of said combustion chamber containment wall and said lid is
closed, said burner assembly will operate at a thermal efficiency of at
least 57% to provide a total energy flux of at least 9.4 KW/m2 in a
cooking zone over said infrared cooking grate with at least 72% of said
total energy flux being infrared radiant energy.

44. The grill of claim 33 wherein said grill further comprises a lid and
a convective cooking grate having a total open area of 20%, and wherein
for each of said burner assemblies, said burner element is configured and
positioned, and said firebox and said V-shaped cross-section of said
combustion chamber containment wall are configured in a manner such that,
when said convective cooking grate is positioned over said upper
discharge opening of said combustion chamber containment wall and said
lid is closed, said burner assembly will operate at a thermal efficiency
of at least 57% to provide a total energy flux of at least 9.4 KW/m2
in a cooking zone over said convective cooking grate with at least 62% of
said total energy flux being infrared radiant energy.

45. The grill of claim 33 wherein when only two of said burner assemblies
are operated in said grill and when (i) said two burner assemblies are
adjacent to each other, (ii) an infrared cooking grate having an open
area of 5% is positioned over each of said two burner assemblies, (iii) a
first of said two burner assemblies is operated at a highest cooking
setting for said first burner assembly which will deliver a high setting
rate of said fuel or said fuel and air mixture to said combustion chamber
of said first burner assembly, and (iv) a second of said two burner
assemblies is operated such that one-half of said high setting rate of
said fuel or said fuel and air mixture is delivered to said combustion
chamber of said second burner assembly, a total resulting energy flux
transmitted into a cooking zone above said second burner assembly will
not be greater than 60% of a total resulting energy flux transmitted into
a cooking zone above said first burner assembly.

46. The grill of claim 45 wherein said grill also includes a third of
said burner assemblies which is adjacent to said second burner assembly
and wherein, when (i) an infrared cooking grate having an open area of 5%
is also positioned over said third burner assembly, (ii) said first
burner assembly is operated at said highest cooking setting, (iii) said
second burner assembly is operated such that one-half of said high
setting rate of said fuel or said fuel and air mixture is delivered to
said combustion chamber of said second burner assembly, and (iv) none of
said fuel or said fuel and air mixture is delivered into said combustion
chamber of said third burner assembly, a total resulting energy flux
transmitted into a cooking zone above said third burner assembly will not
be greater than 16% of said total resulting energy flux transmitted into
said cooking zone above said second burner assembly.

47. The grill of claim 33 wherein when (i) only one of said burner
assemblies is operated in said grill, (ii) an infrared cooking grate
having an open area of 5% is positioned over said one burner assembly,
(iii) said one burner assembly is operated at a highest cooking setting
for said one burner assembly which will deliver a high setting rate of
said fuel or said fuel and air mixture into said combustion chamber of
said one burner assembly, (iv) an infrared cooking grate having an open
area of 5% is also positioned over a second of said burner assemblies
adjacent to said one burner assembly, and (v) none of said fuel or said
fuel and air mixture is delivered into said combustion chamber of said
second burner assembly, a total resulting energy flux transmitted into a
cooking zone above said second burner assembly will not be greater than
13% of a total resulting energy flux transmitted into a cooking zone
above said one burner assembly.

48. The grill of claim 33 wherein, when (i) only two of said burner
assemblies are operated in said grill, (ii) said two burner assemblies
are adjacent to each other, (iii) a convective cooking grate having a
total open area of 20% is positioned over each said two burner
assemblies, (iv) a first of said two burner assemblies is operated at a
highest cooking setting for said first burner assembly which will deliver
a high setting rate of said fuel or said fuel and air mixture to said
combustion chamber of said first burner assembly, and (v) a second of
said two burner assemblies is operated such that one-half of said high
setting rate of said fuel or said fuel and air mixture is delivered to
said combustion chamber of said second burner assembly, a total resulting
energy flux transmitted into a cooking zone above said second burner
assembly will not be greater than 55% of a total resulting energy flux
transmitted into a cooking zone above said first burner assembly.

49. The grill of claim 48 wherein said grill also includes a third of
said burner assemblies which is adjacent to said second burner assembly
and wherein, when (i) a convective cooking grate having a total open area
of 20% is also positioned over said third burner assembly, (ii) said
first burner assembly is operated at said highest cooking setting, (iii)
said second burner assembly is operated such that one-half of said high
setting rate of said fuel or said and air mixture is delivered to said
combustion chamber of said second burner assembly, and (iv) none of said
fuel or said fuel and air mixture is delivered into said combustion
chamber of said third burner assembly, a total resulting energy flux
transmitted into a cooking zone above said third burner assembly will not
be greater than 10% of said total resulting energy flux transmitted into
said cooking zone above said first burner assembly.

50. The grill of claim 33 wherein, when (i) only one of said burner
assemblies is operated in said grill, (ii) a convective cooking grate
having a total open area of 20% is positioned over said one burner
assembly, (iii) said one burner assembly is operated at a highest cooking
setting for said one burner assembly which will deliver a high setting
rate of said fuel or said fuel and air mixture into said combustion
chamber of said one burner assembly, (iv) a convective cooking grate
having an open area of 20% is also positioned over a second of said
burner assemblies adjacent to said one burner assembly, and (v) none of
said fuel or said fuel and air mixture is delivered into said combustion
chamber of said second burner assembly, a total resulting energy flux
transmitted into a cooking zone above said second burner assembly will
not be greater than 8% of a total resulting energy flux transmitted into
a cooking zone above said one burner assembly.

Description:

[0002] Outdoor grilling systems which utilize infrared radiant energy for
cooking are known in the art. The beneficial results which these systems
are capable of providing over conventional convective grills are also
well known. However, a continuing need exists for better and/or lower
cost alternative infrared grills and burner systems which provide greater
thermal efficiencies and other improvements.

[0003] By way of example, but not by way of limitation, a need exists for
better and/or lower cost alternative infrared grills and burner
assemblies which:

[0004] require less metal for fabrication;

[0005] are
less complex and are easier and less costly to fabricate and produce;

[0006] provide better segregation of cooking zones such that the
carryover of heat from one cooking zone to other cooking zones which are
not in operation, or are operating at a lower settings, is significantly
reduced;

[0007] are not limited solely to use with an infrared cooking
grate for infrared cooking but also provide the option of alternatively
using a convective grate for convective cooking.

[0008] A preferred prior art box burner assembly for use in an infrared
grill is disclosed in United States Patent Application Publication No. US
2009/0202688 A1. FIG. 16 of the published application is across-sectional
view of the simplest version of the prior art box burner which comprises:
a single-walled rectangular firebox; a large diameter burner tube which
extends longitudinally through the rectangular firebox and has two rows
of flame ports such that flames are ejected in substantially horizontal
directions from both sides of the tube burner; and two rows of secondary
air openings provided through the bottom of the rectangular box. The two
rows of secondary air openings run parallel with the tube burner on each
side thereof and are spaced laterally outward from the tube burner a
significant distance for feeding the two rows of horizontally flames
ejected in opposite directions from the burner tube.

[0009] An alternative version of the prior art box burner is depicted in
FIG. 4 of the Publication No. US 2009/0202688 A1 wherein; sloped baffles
which extend inwardly as far as the two rows of secondary air openings
are positioned inside of the rectangular burner box; a layer of
insulation is added to the interior wall of the rectangular box beneath
the baffles; and the effective width of the burner element is further
increased significantly by adding a baffle housing arrangement outside of
the large burner tube. As explained in the publication, combustion gasses
from the burner also flow into the spaces formed beneath the internal
baffles so that the entire volume of the rectangular box must be filled
with and heated by the combustion gasses produced by the burner element.
The sloped baffles operate to more effectively direct the infrared
radiant energy emitted from the interior surfaces of the burner box
toward the cooking grate.

[0010] A third embodiment of the prior art box burner is shown in FIG. 17
of Publication No. US 2009/0202688 A1. The version of FIG. 17 employs a
single-walled firebox which is similar to the single-walled rectangular
box of FIG. 16 except that the single-walled box of FIG. 17 has a
trapezoidal cross-sectional shape comprising: a wide horizontal bottom
plate which includes and extends beyond the rows of secondary air
openings on each side of the burner element; a top opening which is wider
than the bottom plate; and sloped sides which extend upwardly from the
outer edges of the bottom plate to the top of the burner box. The
single-walled trapezoidal burner utilizes a wide burner element of the
type shown in FIG. 4 comprising a large baffle housing assembly which
surrounds the large diameter burner tube.

[0011] Based solely upon the illustration of the trapezoidal firebox in
FIG. 17, it appears that the total combustion gas receiving volume of the
single-walled trapezoidal burner box shown would be about 75% of the
volume of a hypothetical rectangular firebox of equal depth and of equal
discharge area width and length (i.e., a hypothetical rectangular firebox
traced over the illustration of the trapezoidal firebox in FIG. 17).

[0012] However, it is important to note that the tracing of a hypothetical
rectangular firebox over FIG. 17 is not relevant to any attempt to
compare the intended or necessary volume of the trapezoidal box of FIG.
17 to the intended or necessary volumes of the rectangular boxes of FIGS.
4 and 16. Publication No. US 2009/0202688 A1 does not show or discuss any
such hypothetical rectangular box and does not teach that the depth and
discharge dimensions of the trapezoidal box are, or even could be, the
same as those of the single-walled rectangular box shown in FIG. 16 or
the baffled rectangular box shown in FIG. 4. Nor does the publication
state or suggest, in any other way, that the construction and dimensions
of the trapezoidal burner can or should be such that the volume of the
trapezoidal firebox would be somewhat less than that of the rectangular
burner of FIG. 16 or the rectangular burner of FIG. 4.

[0013] Consequently, Publication No. U.S. 2009/0202688 A1 neither
discusses nor suggests that any relevant differences actually exist
between the actual volumes or operating characteristics of the fireboxes
of FIGS. 4, 16, and 17. Rather, by requiring that combustion gases must
also fill the volume beneath the sloped internal baffles of FIG. 4, the
publication indicates that the total effective volumes and related
operating characteristics of all of the rectangular and sloped burners
shown in these figures are equalized. Those in the art would readily
understand that the depth and the width of the trapezoidal firebox of
FIG. 17 can be set as necessary to provide essentially the same volume
and operating characteristics as a rectangular box of the type shown in
FIG. 4 or 16.

[0014] Although the box burner assemblies of US 2009/0202688 A1 are
superior to other prior art burners for infrared grilling, the large
interior volumes which they require, along with other requirements and
characteristics of these burners, present difficult barriers for
achieving further improvements in performance and efficiency. Moreover,
even if the actual volume of the trapezoidal box of FIG. 17 of the
publication were assumed to be somewhat smaller, the performance of the
single-walled trapezoidal burner box would still be roughly the same as
the performance of the single-walled rectangular firebox shown in FIG.
16. Although a somewhat smaller volume of the trapezoidal firebox might
tend toward some increase in the temperature of the combustion gas
exiting the top of the trapezoidal firebox, any tendency to provide a
higher firebox temperature would be significantly diminished by the large
excess volume of cold secondary air which enters the bottom of the
firebox through the two rows of air openings. Two rows of air openings
providing a sizable total air intake must be provided in the bottoms of
the trapezoidal and rectangular boxes of FIGS. 16 and 17 in order to
support the two long flame rows extending down the opposite sides of the
elongate burner element.

[0015] Moreover, any significant reduction in the actual constructed
volume of the trapezoidal burner assembly shown in FIG. 17 of Publication
No. US 2009/0202688 A1 would also result in other operational and
certification problems. According to Boyle's law, at given fuel rate, a
significant reduction in volume would produce a corresponding increase in
firebox pressure. Although such a significant increase in pressure would
then in turn theoretically result in an increased operating temperature
in the firebox (Gay-Lussac's law), the increased pressure would also
prevent a sufficient amount of secondary air flow into the firebox to
complete the combustion process. Therefore, the fuel rate to the firebox
would have to be reduced significantly in order to meet industry
certification requirements related to carbon monoxide emissions.

[0016] Unfortunately, however, such a reduction in the fuel rate for the
trapezoidal burner of FIG. 17 would also lead to further problems. Given
the fuel supply pressure and rate necessary to support the two long flame
rows extending along opposite sides of the elongate burner element used
in the assembly, a reduction in the fuel gas supply rate and pressure
sufficient to address the CO emission problems caused by the reduced air
intake would, in turn, render the burner element susceptible to failing
industry wind certification tests which require that the burner must
remain lit, with the grill cover open, when exposed to a wind speed of 10
miles per hour (per ANSI standard, 2.23 of ANSI Z21.58-2007).

SUMMARY OF THE INVENTION

[0017] The present invention provides a grill apparatus and a burner
assembly therefor which provide significant benefits and improvements in
the art. The present invention utilizes a V-shaped burner firebox which
preferably has a firebox volume in the range from about 60% to about 25%,
more preferably from about 55% to about 35%, of that of a rectangular box
burner having (a) the same depth and (b) an upper discharge opening of
the same width and area as the inventive V-shaped firebox. In addition,
the inventive V-shaped burner can provide an even further reduction in
firebox volume by permitting the depth of the firebox to be reduced.

[0018] Regardless of whether the inventive V-shaped burner assembly is
used with an infrared cooking grate or a convective cooking grate, the
inventive assembly provides beneficial increases in the temperature and
pressure within the burner firebox at any given fuel rate, which in turn
operate to (a) improve all types of heat transfer occurring within the
grill to the cooking grate and to the food and (b) allow the amount and
rate of fuel usage to be significantly reduced. These changes
significantly improve the fuel efficiency of the inventive burner and
grill and also operate to increase the proportion of infrared energy
transmitted to the food. Fuel efficiency is further improved as a result
of: (a) the reduced surface area of the firebox, which in turn results in
less convective and radiant heat loss to the atmosphere, and (b) a
reduced intake of excess cold secondary air into the firebox. Further,
the sides of the inventive V-shaped firebox are closer to cooking grate
and are oriented in a manner to provide a higher amount of infrared
radiant heat transfer from the firebox to the cooking grate.

[0019] Moreover the inventive grill and V-shaped burner provide all of
these benefits while also providing significantly improved fuel input
optimization and improved flame performance and management so that the
fuel rate to the firebox can be readily adjusted as necessary in order
to: (a) achieve generally any desired combustion gas temperature and
cooking temperatures, (b) maintain a sufficient air to fuel ratio in the
firebox to provide substantially complete combustion of the fuel and
prevent carbon monoxide emissions, and (c) prevent flame failure with the
grill open at high at wind conditions, even at very low fuel input rates.

[0020] In addition to the methods and advantages listed above, the
inventive grill and V-box burner assembly also: (i) require less metal
for fabrication; (ii) are less complex in design and are therefore easier
and less costly to fabricate; (iii) allow the use of a much simpler and
less expensive tube burner element (e.g., a length of NPS 1/2 inch
diameter pipe); (iv) provide significantly improved flame discharge and
air intake patterns and orientations which increase the life of the
burner element; (v) provide accelerated grease drainage on the slanted
surfaces of the V-shaped firebox, thereby reducing flareups; (vi) provide
significantly improved segregation and zonal performance when a
side-by-side series of two or more of the inventive V-shaped burner
assemblies are installed in a parallel, adjacent relationship in a grill
housing; and (vii) provide a more even distribution of heat to the
cooking grate and in the cooking zone above the grate.

[0021] In one aspect, there is provided a burner assembly for a grill
preferably comprising a firebox having a longitudinally extending
combustion chamber containment wall which defines a combustion chamber
therein. The combustion chamber containment wall has a substantially
V-shaped cross-section and an upper discharge opening. The combustion
chamber containment wall further comprises: a longitudinally extending
bottom, a longitudinally extending left side, and a longitudinally
extending right side. As viewed in the substantially V-shaped
cross-section of the combustion chamber containment wall, the left and
the right sides of the combustion chamber containment wall extend
upwardly from the bottom to the upper discharge opening of the
containment wall. In addition, the left and the right sides of the
combustion chamber containment wall diverge outwardly from, or
proximately from, the bottom of the combustion chamber containment wall
to, or proximately to, the upper discharge opening. Further, the left and
the right sides of the combustion chamber containment wall have lower
ends, at the bottom of the combustion chamber containment wall, which are
in close proximity to each other, or are located substantially at a
shared point.

[0022] This burner assembly also preferably comprises a burner element
extending longitudinally in the combustion chamber above the
longitudinally extending bottom of the combustion chamber containment
wall. The burner element has one or more discharge openings for
delivering a fuel, or a fuel and air mixture, into the combustion
chamber.

[0023] In another aspect, the firebox of the burner assembly preferably
further comprises a longitudinally extending insulating wall positioned
outside of the combustion chamber containment wall. The insulating wall
has a substantially V-shaped cross-section and the insulating wall
further comprises: a longitudinally extending bottom, a longitudinally
extending left side, and a longitudinally extending right side. As viewed
in the substantially V-shaped cross-section of the insulating wall, the
bottom of the insulating wall is positioned below the bottom of the
combustion chamber containment wall and the left and right sides of the
insulating wall extend upwardly from, and diverge outwardly from or
proximately from, the bottom of the insulating wall such that: (i) the
left side of the insulating wall is positioned outside of and adjacent to
the left side of the combustion chamber containment wall such that a left
side insulating gap is formed between the left sides, and (ii) the right
side of the insulating wall is positioned outside of and adjacent to the
right side of the combustion chamber containment wall such that a right
side insulating gap is formed between the right sides. Further, the left
and right sides of the insulating wall have lower ends at the bottom of
the insulating wall which are in close proximity to each other or are
located substantially at a shared point.

[0024] In another aspect, there is provided a burner assembly for a grill
preferably comprising: (a) a double-walled firebox having a V-shaped
cross-section and (b) a burner element. The double-walled firebox
preferably comprises a longitudinally extending inner combustion chamber
containment wall having: a V-shaped cross-section, a longitudinally
extending bottom, a longitudinally extending left side, and a
longitudinally extending right side. A combustion chamber is defined in
the inner wall between the left and the right sides of the inner wall. In
the V-shaped cross-section of the inner wall, the left and right sides of
the inner wall extend upwardly from, and diverge outwardly from or
proximately from, the bottom of the inner wall.

[0025] The double-walled firebox also preferably comprises a
longitudinally extending outer insulating wall positioned outside of and
adjacent to the inner wall. The outer wall has: a V-shaped cross-section,
a longitudinally extending bottom, a longitudinally extending left side,
and a longitudinally extending right side. In the V-shaped cross-section
of the outer wall, the left and the right sides of the outer wall extend
upwardly from, and diverge outwardly from, or proximately from, the
bottom of the outer wall.

[0026] In this burner assembly, the bottom of the outer wall will
preferably be positioned below the bottom of the inner wall. In addition,
the left side of the outer wall will preferably be positioned outside of
the left side of the inner wall such that a left side insulating gap is
formed between the left side of the inner wall and the left side of the
outer wall. Further, the right side of the outer wall will preferably be
positioned outside of the right side of the inner wall such that a right
side insulating gap is formed between the right side of the inner wall
and the right side of the outer wall. These insulating gaps will
preferably be air insulation gaps but can alternatively be filled or
partially filled with any desired type of insulating material. The
insulating gaps will also preferably be formed so that combustion gases
produced in the combustion chamber are prevented from entering the
insulating gaps.

[0027] The burner element used in the burner assembly will preferably
extend longitudinally in the combustion chamber above the bottom of the
inner wall. In addition, the burner element will preferably have one or
more openings for delivering a fuel or a fuel and air mixture into the
combustion chamber. The burner element will most preferably comprise a
pipe or other conduit having one or more openings formed through the
longitudinally extending top thereof for delivering the fuel or fuel and
air mixture into the combustion chamber.

[0028] In the V-shaped cross-section of the inner combustion chamber
containment wall of the firebox, the left and the right sides of the
inner wall have lower ends at the bottom of the inner wall which are in
close proximity to each other or are located at or substantially at a
shared point (preferably a vertex). Similarly, in the V-shaped
cross-section of the outer wall of the firebox, the left and the right
sides of the outer insulating wall have lower ends at the bottom of the
outer wall which are in close proximity to each other or are located at
or substantially at a shared point (preferably a vertex).

[0029] As used herein and in the claims in reference to the lower ends of
the left and right sides of the combustion chamber containment wall and
insulating wall, the term "close proximity" means that the lower ends of
the left and the right sides are not located more than 1/2 inch apart.
For each of the inner and outer walls, the lower ends of the left and
right sides of the wall will preferably not be located more than 3/8 inch
apart, more preferably not more than 1/4 inch apart, and will most
preferably be located at or substantially at a shared point (preferably a
vertex).

[0030] As also used herein and in the claims in reference to the lower
ends of the left and right sides of the combustion chamber containment
wall and the insulating wall, the term "proximately from the bottom"
means from a location which is not more than 1/2 inch, more preferably
not more than 1/4 inch and most preferably not more than 1/8 inch, from
the bottom. Similarly, as used herein and in the claims in reference to
the left and the right sides of the combustion chamber containment wall,
the term "proximately to the upper discharge opening" means to a location
which is not more than 1/2 inch, more preferably not more than 1/4 inch
and most preferably not more than 1/8 inch, below the upper discharge
opening.

[0031] In another aspect, there is provided a grill which preferably
comprises a housing having therein one inventive burner assembly, or two,
three, or more inventive burner assemblies, of any type described herein.
The grill preferably comprises a plurality of such burner assemblies
positioned adjacent to each other in the housing in a parallel
arrangement.

[0032] When the grill comprises a plurality of burner assemblies, a
corrugated single walled firebox can preferably be made, for example,
either by forming from a deep drawn sheet metal or by lap welding
multiple sheet metal pieces.

[0033] Further aspects, features, and advantageous of the present
invention will be apparent to those of ordinary skill in the art upon
examining the accompanying drawings and upon reading the following
detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is a cutaway side perspective view of an embodiment 2 of the
grill provided by the present invention using three inventive
double-walled, V-shaped burner assemblies 10 and an infrared cooking
grate 12.

[0044] An embodiment 2 of an inventive grill for outdoor cooking is
depicted in FIGS. 1 and 2. The inventive grill 2 preferably comprises: a
grill housing 4; a pivotable lid, or other cover 6, for opening and
closing the top of the grill housing 4; at least one inventive V-shaped
burner assembly 10 positioned in the grill housing 4; a food support
grate 12, preferably positioned at or proximate to the top(s) of the
inventive burner assembly or assemblies 10; a stand 14 for supporting the
grill housing 4; and a grease drip pan 16 provided below the burner
assembly or assemblies 10. The embodiment of the inventive grill 2
depicted in FIG. 2 includes a series of three inventive burner assemblies
10 which are positioned adjacent to each other in a parallel arrangement.

[0045] The embodiment 10 of each of the inventive V-shaped burner
assemblies shown in FIG. 2 comprises: a double-walled firebox 20 which
extends longitudinally in the grill housing 4 from the front to the back
of the housing 4 and has a V-shaped cross-section 25 as illustrated in
FIG. 2; a combustion chamber 27 within the V-shaped firebox 20 which has
an upper discharge opening 26 at the top of the V-shaped firebox 20; a
discharge opening width 23; a burner element 35 extending longitudinally
in the V-shaped firebox 20 for delivering fuel or a fuel and air mixture
into the combustion chamber 27; a longitudinally extending flame taming
shield 31 positioned between the burner element 35 and the food support
grate 12; and one or more (preferably a series) of air flow passages 32
preferably provided in the bottom 34 of the V-shaped firebox 20 for
delivering air (preferably secondary air) into the combustion chamber 27.

[0046] The double-walled, V-shaped firebox 20 used in the inventive burner
assembly 10 preferably comprises: a longitudinally extending inner
combustion chamber containment wall 22 having a V-shaped vertical
cross-section; a longitudinally extending, V-shaped outer insulating wall
24 which is positioned outside of and preferably runs substantially
parallel to the inner wall 22; and a longitudinally extending insulating
gap 26 which is provided between the inner wall 22 and the outer wall 24
and also has a V-shaped vertical cross-section. The combustion chamber 27
of the burner assembly 10 is defined by (i.e., contained within the
interior of) the combustion chamber containment wall 22.

[0047] The V-shaped inner combustion chamber containment wall 22 has a
longitudinally extending left side 28 and a longitudinally extending
right side 30. The left and right sides 28 and 30 extend upwardly from
the bottom 29 of the inner wall 22. The left and right sides 28 and 30
preferably extend upwardly to, and also preferably define the left and
right side limits of, the combustion chamber discharge opening 26 at the
top of the firebox 20. In addition, in the cross-sectional view, the left
and right sides 28 and 30 diverge outwardly, in a substantially V-shaped
manner, from, or proximately from, the bottom of the combustion chamber
containment wall 22 to, or proximately to, the combustion chamber
discharge opening 26. The outward divergence of the left and right sides
28 and 30 preferably begins not more than 1/4 inch from, more preferably
not more than 1/8 inch from, and most preferably at, the bottom 29 of the
inner wall 22. Similarly, the outward divergence of the left and right
sides 28 and 30 preferably ends not more than 1/4 inch from, more
preferably not more than 1/8 inch from, and most preferably at, the upper
discharge opening 26. Consequently, although in the cross-sectional view
a short lower end portion and/or a short upper end portion of the sides
28 and 30 can be vertical or otherwise non-diverging, the sides 28 and 30
will most preferably be continuously diverging, in a straight or a curved
manner, from the bottom 29 the inner wall 22 to the upper discharge
opening 26.

[0048] The V-shaped outer insulating wall 24 also comprises longitudinally
extending left and right sides 34 and 36 which preferably run
substantially parallel to and are spaced apart from the left and right
sides 28 and 30 of inner combustion chamber containment wall 22. As a
result, left and right insulating gaps 38 and 40 are formed between the
inner and outer walls 22 and 24. The left and right sides 34 and 36 of
the outer wall 24 extend upwardly from the bottom 42 of the outer wall
24. The bottom 42 of the outer wall 24 is preferably positioned below and
spaced apart from the bottom 29 of the inner wall 22. As with the inner
wall 22, the left and right sides 34 and 36 of the outer wall 24 also
diverge outwardly from, or proximately from, the bottom 42 of the outer
wall 24. The divergence preferably begins not more than 1/4 inch from,
more preferably not more than 1/8 inch from, and most preferably at, the
bottom 42 of the outer wall 24.

[0049] The widths 44 and 46 of the left and right insulating gaps 38 and
40 of the double-walled, V-shaped firebox 20 will preferably be at least
0.2 inch. The widths of the insulating gaps will more preferably be in
the range of from about 0.2 to about 0.6 inch and will most preferably be
about 0.5 inch. The insulating gaps 38 and 40 will preferably be air
insulating gaps or other empty (i.e., unfilled) gaps but can
alternatively be filled or partially filled with one or more layers of
insulating material. Examples of suitable insulating materials include,
but are not limited to high temperature insulating materials such as
fiber glass, calcium silicate, cellular glass, mineral wool, etc.

[0050] Regardless of whether the insulating gaps 38 and 40 are empty or
have an insulating material therewith, the combustion chamber containment
wall 22 and the insulating gaps 38 and 40 are preferably formed so that
no combustion gas from the combustion chamber 27 is allowed to enter the
gaps 38 and 40.

[0051] As illustrated in FIG. 2, in the vertical cross-section of the
firebox 20, the left and right sidewalls 28 and 30 of the inner wall 22
and the left and right sidewalls 34 and 36 of the outer wall 24 each
extend upwardly and diverge outwardly from the respective bottoms 29 and
42 of the inner and outer walls in a substantially straight line. It will
be understood, however, that the upwardly diverging left and right sides
28 and 30 of the V-shaped inner wall 22 and the upwardly diverging left
and right sides 34 and 36 of the V-shaped outer wall 24 can alternatively
be curved (e.g., convex or concave) or have other nonlinear shapes, so
long as they retain a diverging, substantially V-shaped appearance.

[0052] In addition, in the V-shaped cross-section of the combustion
chamber containment wall 22, the left and right sides 28 and 30 of the
combustion chamber containment wall 22 have lower ends 43 and 44 at the
bottom 29 of the wall 22 which are in close proximity to each other
(i.e., are not more than 1/2 inch apart). The lower ends 43 and 44 of the
sides 28 and 30 of the combustion chamber containment wall 22 are
preferably not more than 3/8 inch apart. The lower ends 43 and 44 are
more preferably not more than 1/4 inch apart and are still more
preferably not more than 1/8 inch apart. Most preferably, the lower ends
43 and 44 of the left and right sides 28 and 30 of the combustion chamber
containment wall 22 and the bottom 29 of the wall 22 are all located at
and constitute, or are at least substantially located at and
substantially constitute, a common, shared point which will thus define,
or at least substantially define, a bottom vertex point for the
substantially V-shaped inner wall 22.

[0053] Similarly, in the substantially V-shaped cross-section of the
firebox outer insulating wall 24, the left and right sides 34 and 36 of
the outer wall 24 have lower ends 47 and 49 at the bottom 42 of the outer
wall 24 which are preferably not more than 1 inch apart. The lower ends
47 and 49 of the sides 34 and 36 of the outer wall 24 are more preferably
not more than 1/2 inch apart. The lower ends 47 and 49 and are more
preferably not more than 1/4 inch apart and are still more preferably not
more than 1/8 inch apart. Most preferably, the lower ends 47 and 49 of
the left and right sides 34 and 36 of the outer wall 24 and the bottom 42
of the outer wall 24 are all located at and constitute, or are at least
substantially located at and substantially constitute, a common shared
point which will thus define, or at least substantially define, a bottom
vertex point for the substantially V-shaped outer wall 24.

[0054] It will thus be understood that the bottoms 29 and 42 of the
combustion chamber containment wall 22 and the insulating outer wall 24,
as seen in the vertical cross-section of the V-shaped firebox 20, can be
short segments (preferably not more than 1/2 inch, more preferably not
more than 1/4 inch, and more preferably not more than 1/8 inch) which are
flat or curved, but will most preferably constitute, or at least
substantially constitute, points which form vertices for the combustion
chamber containment wall 22 and the outer insulating wall 24.

[0055] Consequently, as used here and in the claims, it will be apparent
that the term "substantially V-shaped" refers to and encompasses strict
V-shapes, other straight V-shapes, rounded or curved V-shapes, and
V-shapes having short segments which are straight and/or rounded.

[0056] However, regardless of whether the bottoms 29 and 42 of the inner
and outer walls 22 and 24 are pointed, flat, or rounded, or whether the
sides 28, 30, 34, and 36 of the inner and outer walls 22 and 24 are
substantially straight or curved, the V-shaped firebox 20 will preferably
be substantially symmetrical with respect to a central vertical plane 48
extending longitudinally through the firebox 20 and will preferably be
configured such that, for each side 28, 30, 34, and 36, the angle of
divergence 50 or 51 from the vertical plane 48 of a line 52 or 54
extending from the lower end 43, 44, 47, or 49 of the side 28, 30, 34, or
36, through the outermost endpoint 56 or 58 of the side 28, 30, 34, or 36
will not be greater than 70° and will more preferably be in the
range of from about 35° to about 65°. The angle of
divergence 50 or 51 will most preferably be in the range from about
40° to about 50°.

[0057] In addition, although the sizes and shapes of the substantially
V-shaped inner wall 22 and the substantially V-shaped outer wall 24 of
the double-walled burner assembly 10 need not be identical, the shapes
and/or the sizes of the V-shaped inner wall 22 and the V-shaped outer
wall 24 will most preferably be the same or substantially the same.

[0058] The inner combustion chamber containment wall 22 will preferably
have sufficient sturdiness and heat resistance to provide structural
support for the burner assembly 10 and to withstand the combustion
temperatures and conditions produced in the combustion chamber 27.
Examples of materials suitable for forming the substantially V-shaped
inner wall 22 of the firebox 20 include, but are not limited to stainless
steel, cold rolled steel, porcelain coated steel, etc.

[0059] The outer insulating wall 24 can be, but for cost reduction and
other reasons preferably will not be used to provide significant
structural support for the burner assembly 10. Consequently, examples of
materials preferred for forming the V-shaped outer wall 24 of the firebox
20 include, but are not limited to aluminized steel, galvanized steel,
bright finish stainless steel, any highly polished steel etc.

[0060] Preferably, for cost reduction and improved operation, the inner
and outer walls 22 and 24 of the firebox 20 will be formed and/or coated
in a manner such that: (a) the inner surface 60 of the inner wall 22 has
an emissivity of anywhere from 0.01 to 0.95, (b) the outer surface 62 of
the inner wall 22 will have an emissivity of not more than 0.6, (c) the
inner surface 64 of the outer wall 24 will have an emissivity of not more
than 0.6, and (d) the outer surface 66 of the outer wall 24 will have an
emissivity of not more than 0.6.

[0061] To achieve these preferred emissivity characteristics of the inner
surface 60 and the outer surface 62 of the inner wall 22, the inner wall
22 will most preferably be formed of stainless steel. As another example,
porcelain coated steel can be used with some minor reduction in
performance.

[0062] To the achieve the above-described preferred emissivity
characteristics for the inner surface 64 and outer surface 66 of the
outer wall 24, the outer wall 24 will most preferably be formed of
polished aluminized steel.

[0063] Although other types of burner elements and flame port arrangements
can alternatively be used, the burner element 35 used in the inventive
burner assembly 10 will preferably be a substantially straight tube-type
burner (e.g., a cylindrical pipe or other conduit, preferably having an
inside diameter of about 1/2 inch, or preferably any other NPS 1/2 inch
pipe) which extends longitudinally in the firebox 20. The burner element
35 has one or more, preferably a series, of flame discharge ports 68
therein for delivering fuel, preferably a fuel and air mixture, into the
firebox combustion chamber 27. The burner element 35 is preferably
substantially centrally located in the firebox combustion chamber 24 with
the burner port(s) 68 preferably being formed longitudinally along the
top of the burner element 35, most preferably at least substantially in
alignment with the vertical plane of symmetry 48.

[0064] The burner element 35 will also preferably extend longitudinally
above the air passage(s) 32 formed along the longitudinally extending
bottom 34 of the firebox 20. The air passage(s) 32 through the bottom 34
of the firebox 20 will preferably comprise (a) one or more, preferably a
series of, openings 70 formed through and along the longitudinally
extending bottom 42 of the outer insulating wall 24 and (b) one or more,
preferably a series, of openings 72 formed through and along the
longitudinal extending bottom 29 of the inner combustion chamber
containment wall 22. The air opening(s) 72 in the bottom 29 of the inner
wall 22 is/are in fluid communication with the one or more air openings
70 formed through the bottom of the outer wall 24. The air opening(s) 72
in the bottom 29 of the inner wall 22 and the air opening(s) 70 in the
bottom 42 of the outer wall 24 will also preferably be at least
substantially in alignment with the vertical plane of symmetry 48.

[0065] By preferably using a single row of burner discharge ports 68
running along the top of a tube burner element 35, the inventive burner
assembly 10 is capable of operating at a desired or necessary lower fuel
input rate for the inventive low volume firebox 20 in order to optimize
the combustion chamber temperature and ensure sufficiently complete
combustion to meet CO emission requirements while at the same time
maintaining a stable flame under wind certification conditions. In the
preferred single row arrangement, the flame discharge port(s) 68 and the
box air openings 70 and 72 are all substantially in alignment with the
vertical plane of symmetry 48. This top ported design increases the life
of the burner element 35 by substantially preventing any flame wrap
around from the sides of the burner element to the top thereof which
happens on the side ported burners.

[0066] The configuration, the angles of divergence 50 and 51, and the
straight, curved, or other diverging shape of the left and right sides 28
and 30 of the combustion chamber combustion wall 22 will preferably be
such that the total volume of the substantially V-shaped firebox
combustion chamber 27 (i.e., the total combustion gas receiving volume of
the firebox 20) does not exceed 65% of the volume of a corresponding
rectangular firebox having an identical depth, an identical upper
discharge opening area, and an identical discharge opening width. More
preferably, the total volume of the combustion chamber 27 of the V-shaped
firebox 20 will not be greater than 60%, more preferably less than 55%,
more preferably less than 52%, and more preferably not more than 50%, of
the volume of the corresponding rectangular firebox. The volume of the
combustion chamber 27 will preferably be in a range of from about 25% to
about 60%, more preferably from about 35% to about 55%, and most
preferably from about 40% to about 52%, of the volume of the rectangular
firebox having an identical depth, an identical upper discharge opening
area, and an identical discharge opening width.

[0067] The creation of a V-shaped firebox having a volume of less than 50%
of the corresponding rectangular box can be accomplished, for example, by
using a curved V-shape, most preferably a bird wing V-shape, as discussed
below. In addition, the inventive V-shaped burner can provide an even
further reduction on firebox volume by allowing the depth of the
combustion chamber to be significantly reduced without causing a flame
impingement failure.

[0068] The firebox combustion chamber 27 and the positioning of the burner
element 35 therein will preferably be such that the top port(s) 68 of the
burner element 35 are spaced at least 2 inches, more preferably from
about 2 to about 4 inches and most preferably from about 2 to about 3
inches, from the upper discharge opening 26 at the top of the firebox 20.
The bottom of the burner element 35 will preferably be spaced at least
1/2 inches above the bottom 29 of the firebox inner wall 22. The bottom
of the burner element 35 will more preferably be spaced from about 1/2 to
about 3/4 inches above the bottom 29 of the firebox inner wall 22.

[0069] The flame taming shield 31 of the inventive burner assembly 10 will
preferably be positioned at least 1/2 inches, more preferably from about
1/2 to about 1 inch, above the port(s) 68 in the top of the burner
element 35. The flame taming shield 30 will also preferably be positioned
at least 1 inch, more preferably from about 1 to about 2 inches, below
the firebox discharge opening 26.

[0070] The fuel used in the inventive burner assembly 10 will preferably
be propane or other fuel of a type suitable for use in gas powered grills
and will also preferably be mixed with primary air prior to being
delivered into the firebox combustion chamber 27 by the burner element
35. In accordance therewith, by way of example, the inventive grill 2 and
the inventive burner assembly 10 illustrated in FIGS. 1 and 2 further
comprise: a fuel supply line 74 for delivering fuel from a fuel tank or
other fuel source (not shown); a control knob 76 (preferably a separate
control knob for each burner assembly 10) for selectively controlling the
fuel rate and for shutting off the flow of fuel to the burner element 35;
and a venturi element or other air induction or injection device 78 for
drawing or injecting primary air into the burner element 35 for mixture
with the fuel.

[0071] Because of the significantly reduced firebox combustion chamber
volume and the configuration of the inventive V-shaped burner assembly
10, the inventive burner assembly 10 requires significantly less fuel to
operate than previous box-type burners or other burners used in infrared
systems, and provides a higher percentage of infrared radiant cooking
energy. When used with an infrared cooking grate comprising a solid glass
plate having inverted U-shaped cooking ribs thereon and without any grill
lid, the inventive double-walled, V-shaped burner assembly 10 shown in
FIG. 2 will provide an overall thermal efficiency of at least 40% (more
preferably at least 42%, and more preferably at least 45%) with at least
75%, (more preferably at least 78% and more preferably at least 80%) of
the total cooking energy flux delivered to the cooking zone on top of the
cooking grate being in the form of infrared radiant energy.

[0072] The food support grate 12 depicted in FIG. 2 for the inventive
grill 2 is a one piece infrared cooking grate. It will be understood,
however, that other types of infrared cooking grates can be used in the
inventive grill 2 including, for example, two piece infrared grates or
infrared cooking grates having more than two pieces.

[0073] An alternative embodiment 100 of the inventive grill is depicted in
FIG. 3. The inventive grill 100 is substantially identical to the
inventive grill 2 except that (a) the food support grate 102 used in the
inventive grill 100 is a convective cooking grate and (b) the flame
taming shields 104 employed in the inventive convective grill assembly
100 are wider than those used in the inventive infrared grill assembly 2.
The flame taming shields 104 of the inventive convective grilling system
100 also preferably have flow openings 106 formed therethrough to allow
grease drippings to drain therefrom and/or permit some degree of upward
gas flow through the shield 104. The ability to also use the inventive
V-shaped burner for convective cooking using a convective (i.e., open)
cooking grate is a significant benefit and advantage of the inventive
burner assembly versus the prior art burners used heretofore in infrared
cooking grills.

[0074] Because of the greater amount of flow which will occur through an
open convective cooking grate 102 as used in grill 100, versus an
infrared cooking grate 12 as used in grill 2, the wider flame taming
shields 104 employed in the convective grill 100 are preferably used in
order to better distribute the combustion gas before it reaches the
bottom of the cooking grate 102. This helps to ensure that the flow
through the open convective cooking grate 102 is evenly distributed and
does not simply bypass the portions of the grate located above the outer
areas of the burner firebox.

[0075] In contrast, because the infrared grate system 12 of grill 2 will
typically allow much less, or perhaps even no, air flow therethrough, the
infrared grate 12 itself is of much greater assistance in distributing
the heat and combustion gas flow produced by the burner element 35.
Consequently, although a flame taming shield 30 will preferably still be
used in the infrared system 2 in order to further ensure even heating
across the entire cooking grate, the shield 30 in the infrared system can
be significantly narrower in width.

[0076] An alternative embodiment 350 of the inventive V-shaped burner and
a grilling system 352 using a plurality (e.g., three) of the inventive
V-shaped burners 350 are illustrated in FIGS. 8 and 9. The burner
assembly 350 and grilling system 352 are identical to the inventive
burner assembly 10 and grill 2 described above except that the
substantially V-shaped burner assembly 350 is a single-walled burner
which does not have an insulating wall positioned outside of the
combustion chamber containment wall 354. Consequently, if the cooking
grate 356 used in the grilling system 352 is an infrared cooking grate
having an open area of 5% and the grill lid is closed, the inventive
burner assembly 350 will provide (a) a total energy flux of at least 9.4
KW/m2 (more preferably at least 9.6 KW/m2), and (b) an overall
thermal efficiency of at least 57%, (more preferably at least 59%, more
preferably at least 60%, more preferably at least 65%, and more
preferably at least 70%) with (c) at least 72% (more preferably at least
74%, more preferably at least 75%, and more preferably at least 80%) of
the total cooking energy flux delivered to the cooking area being
infrared radiant energy.

[0077] Alternatively, if the grate 356 is a convective cooking grate
having an open area of 20%, the inventive burner assembly 350 will
provide (a) a total energy flux of at least 9.4 KW/m2 (more
preferably at least 9.6 KW/m2) and (b) a thermal efficiency of at
least 57%, (more preferably at least 59%, more preferably 60%, and more
preferably 65%) with an infrared percentage of at least 60% (more
preferably at least 62%, more preferably at least 64%, and more
preferably at least 65%).

[0078] Another alternative grilling assembly 105 using an adjacent pair of
burner assemblies formed in accordance with an embodiment 110 of the
present invention is schematically illustrated in FIG. 4. Each of the
inventive double-walled, V-shaped burner assemblies 110 depicted in FIG.
4 is essentially the same as the inventive burner assembly 10 depicted in
FIG. 2 except that (a) the left and right sides 128 and 130 of the inner
combustion chamber containment wall 122 and the left and right sides 134
and 136 of the outer insulating wall 124 of the firebox 127 are curved
such that the V-shaped cross-section of the firebox 120 is a birdwing V
shape and (b) the particular embodiment shown in FIG. 4 uses a wider
flame taming shield 131 of a type better suited for a convective cooking
grate 112. The use of a birdwing or other curved V shape of this type can
be beneficial in that, for example, the volume of the firebox 127 can be
reduced to a size which is even less than 50% of the volume of a
corresponding rectangular box having an identical depth, an identical
discharge opening area, and an identical discharge opening width. The
degree of curvature of the left and right sides of the curved V firebox
27 can be such as to provide a working firebox volume as small as even
25% of the volume of the corresponding rectangular box.

[0079] Yet another alternative embodiment 400 of the inventive curved V
burner is illustrated in FIG. 10. The inventive curved V burner assembly
400 is identical to the curved V burner assembly 110 except that the
burner assembly 400 is a single-walled burner which does not have an
insulating wall positioned outside of the combustion chamber containment
wall 454.

[0080] By way of example, but not by way of limitation, when producing an
individual double-walled, V-shaped burner assembly 10 or double-walled
birdwing V-shaped assembly 110, the double-walled firebox of the single
burner assembly will preferably be fabricated by the steps of deep
drawing or lap welding inner wall 22 and outer wall 24 from sheet metal.
The pieces can be coated, if desire, and then attached to the main frame
or walls of the grill housing. A top ported 1/2'' to 5/8'' tube burner
can be screwed or clipped to the bottom of the firebox. A formed flame
taming shield can be clipped in place and finally the weld assembled
cooking grate will be placed freely on the top of firebox edges.

[0081] By way of example, but not by way of limitation, when producing a
set of multiple, adjacent, parallel, double-walled burner assemblies 10
as illustrated in FIG. 2 or double-walled birdwing V-shaped assemblies
110 as illustrated in FIG. 4, the double-walled, parallel, adjacent
fireboxes of the multiple burner assemblies can be fabricated, for
example, by attaching together multiple modular units side-by-side either
by screws or magnets. Alternatively, as another example, multiple
fireboxes can be formed as a single corrugated firebox either by deep
drawing a piece of sheet metal or by lap welded fabrication.

[0083] Thus, for example, in reference to FIG. 2, the inventive
double-walled, V-shaped burner assemblies 10 are effective, due to their
construction and configuration as described above, for significantly
preventing the operation of the left side burner assembly 10a from
affecting the cooking zone 15b above the central burner assembly 10b or
from affecting the cooking zone 15c above right side burner assembly 10c.
Similarly, the operation of central burner assembly 10b and/or the right
side burner assembly 10c is significantly prevented from affecting the
cooking zone 15a above the left side burner assembly 10a. The cooking
zones 15a, 15b, and 15c are located at or proximate to the top of the
food support grate 12.

[0084] Such segregation of the cooking zones 15a, 15b, and 15c not only
improves thermal efficiency, but also improves and enhances the ability
to conduct separate, distinct cooking operations above the individual
burner assemblies 10a, 10b, and 10c at significantly different burner
settings.

[0085] The ability of the inventive system to minimize the heat carryover
between burner assemblies, and thus significantly reduce the effect which
the operation of any individual burner assembly has on other cooking
zones, can be illustrated using the inventive infrared grill 2 shown in
FIG. 2 with an infrared cooking grate with 5% open area, for example, by:
(a) operating the right side burner assembly 10a at a high cooking
setting wherein a high setting rate (e.g., about 35 BTU/hour per square
inch) is delivered to the firebox combustion chamber 27 of the burner
assembly 10a; (b) operating the central burner assembly 10b at a lower
cooking setting such that one-half of the high rate of fuel delivered to
burner assembly 10a is delivered to the central burner assembly 10b; and
(c) leaving the right side burner assembly 10c off so that no fuel is
delivered thereto.

[0086] Due to the construction of the inventive burner assemblies 10a,
10b, and 10c wherein the V-shaped fireboxes 20 are more isolated and are
separated by gaps 80 having an inverted V-shape, the carryover of heat
energy from any one burner assembly to the others will be significantly
reduced such that a total energy flux transmitted into the cooking plane
15b above the central burner assembly 10b will not be greater than 60%
(more preferably not more than 58% and more preferably not more than 55%)
of the total energy flux transmitted into the cooking plane 15a above the
left side burner assembly 10a. At the same time, the total energy flux
transmitted into the cooking zone 15c above the right side burner
assembly 10c, which is turned off, will not be greater than 16% (more
preferably not more than 14% and more preferably not more than 12%) of
the total energy flux transmitted into the central cooking zone 15b.

[0087] Similarly, if when operating burner assemblies 10a, 10b, and 10c in
this same manner, the infrared food support grate 12 of FIG. 2 is
replaced with a convective grate 102 as illustrated in FIG. 3 having 20%
open area, the total energy flux transmitted into the central cooking
zone 15b will not be greater than 55% (more preferably not more than 52%
and more preferably not more than 51%) of the total energy flux
transmitted into the left side cooking zone 15a. At the same time, the
total energy flux transmitted into the right side cooking zone 15c will
not be greater than 10% (more preferably not more than 8% and more
preferably not more than 6%) of the total energy flux into the central
cooking zone 15b.

[0088] In another example using the inventive grill 2 illustrated in FIG.
2 having an infrared cooking grate 12, if the left side burner assembly
10a is operated at the high cooking setting and the central burner
assembly 10b and the right side burner assembly 10c are both turned off,
the construction of the inventive burner assemblies 10a, 10b, and 10c and
the effective separation of the V-shaped fireboxes 20 thereof are such
that, with an infrared cooking grate having 5% open area, the total
energy flux into the central cooking zone 15b above the infrared grate 12
will not be greater than 13% (more preferably not more than 10%) of the
total energy flux into the left side cooking zone 15a. Similarly, under
this same operation but using the convective cooking grate 102 having 20%
open area, the total energy flux transmitted into the central cooking
zone 15b will not be greater than 8% (more preferably not more than 5%)
of the total energy flux transmitted into the left side cooking zone 15a.

Example I

[0089] The three-zone infrared grills 2 and 100 shown in FIGS. 2 and 3
employing double-walled, straight V-shaped burner fireboxes 20 were
compared to (a) an otherwise identical three-burner grill assembly using
a firebox similar to prior art partitioned, rectangular firebox 200 as
illustrated in FIG. 5 except that double-walled insulating partitions
between the cooking zones and a double outer wall were used and (b) an
otherwise identical three-burner grill using the modified double-walled
version of the non-partitioned, rectangular firebox 250 illustrated in
FIG. 6.

[0090] In all of the grills 2, 100, 200 and 250, the burner assemblies had
the same depth and had upper discharge opening areas which were identical
in size.

[0091] In each of the grill systems, all three burners were operated using
a propane and air mixture at a fuel and air input setting of 16.23
KW/m2 using both (a) an infrared cooking grate with 5% open area and
(b) an open convective cooking grate with 20% open area. Experimental
data showing the comparative performance (with the grill lid closed) of
the inventive double-walled, V-shaped system versus the grill using the
partitioned rectangular firebox and the grill using the non-partitioned
rectangular firebox are provided in Table I.

[0092] Consequently, even when the rectangular fireboxes were improved by
using double insulating walls, the cooking energy flux provided by the
inventive double-walled, V-shaped burner assembly was: (a) 8.36% greater
than the flux provided by the rectangular, partitioned burners when using
the infrared cooking grate, (b) 5.38% greater than the flux provided by
the partitioned, rectangular burners when using the convective cooking
grate, (c) 11.12% greater than the flux provided by the non-partitioned,
rectangular burners when using the infrared cooking grate, and (d) 12.02%
greater than the flux provided the non-partitioned, rectangular burners
when using the convective cooking grate.

[0093] In addition, the portion of the total cooking energy flux desirably
constituting infrared radiant energy when using the inventive
double-walled, V-shaped burner assemblies was: (a) 6.83% greater than
provided by the partitioned, rectangular burners when using the infrared
cooking grate, (b) 6.78% greater than provided by the partitioned,
rectangular burners when using the convective cooking grate, (c) 7.58%
greater than provided by the non-partitioned, rectangular burners when
using the infrared cooking grate, and (d) 17.14% greater than provided by
the non-partitioned, rectangular burners when using the convective
cooking grate.

Example II

[0094] The inventive double-walled, V-shaped burner assemblies 10 of FIGS.
1 and 2 are again compared to (a) the otherwise identical grill using the
rectangular, partitioned firebox system described in Example I and (b)
the otherwise identical grill using the rectangular, non-partitioned box
described in Example I. In this test, the three parallel burner
assemblies in each of these systems were operated using a propane and air
mixture such that (a) the left side burner was placed at a high fuel and
air input setting of 16.23 KW/m2, (b) the central burner assembly
was operated at a lower setting providing one-half of the fuel input rate
as the high setting of the left side burner assembly, and (c) the right
side burner assembly was turned off. Comparative runs were performed with
both (a) an infrared cooking grate having 5% open area and (b) an open
convective cooking grate with 20% open area.

[0095] Experimental data showing the amount of flux carryover between the
three cooking zones for the inventive double-walled, V-shaped system
versus the grill using the partitioned, rectangular firebox system and
the grill using the non-partitioned, rectangular system are shown in
Table II.

[0096] The primary reason(s) for this significantly improved performance
provided by the inventive V-shaped burner assemblies is that the V-shape
of the burner firebox creates inverted V-shaped gaps 80 between the
adjacent fireboxes 20 in the inventive grill which greatly reduce or
prevent heat transfer between adjacent boxes.

Example III

[0097] A single, individual inventive double-walled, V-shaped burner
assembly 10 as illustrated in FIG. 2 was compared to an otherwise
identical burner using a prior art double-walled rectangular firebox 300
with angled reflectors 302 and 304 as illustrated in FIG. 7. The
inventive V-shaped burner assembly and the prior art rectangular burner
had identical depths and had upper discharge opening areas of the same
width and size. Each of these burner assemblies was operated using a
propane and air mixture at a fuel/energy input rate of 32.8 KW/m2.
Grills were tested using an infrared grate system comprising a solid
glass plate radiator having inverted U-shaped cooking ribs thereon. The
grills were operated without any lid. Experimental data show that the
inventive double-walled, V-shaped burner operated at an average thermal
efficiency of about 42.32% and provided a total heat flux of 13.91
KW/m2 with 78.72% of the total heat flux being infrared radiant
energy.

[0098] In comparison, the burner using the prior art double-walled,
rectangular firebox 300 with angled deflectors 302 and 304 operated at an
average thermal efficiency of about 38.42% and provided a total heat flux
of 12.62 KW/m2 with 76.19% of the total heat flux being infrared
radiant energy.

[0099] Consequently, although the prior art firebox 300 included angled
deflectors, the energy efficiency and infrared percentage obtained using
the prior art firebox 300 were significantly less primarily due to: the
greater volume of the prior art firebox 300; the amount of energy wasted
in heating the volume beneath the deflectors 302 and 304; and the much
improved combustion chamber provided by the inventive V-shaped firebox.

[0100] Thus, the present invention is well adapted to carry out the
objectives and attain the ends and advantages mentioned above as well as
those inherent therein. While presently preferred embodiments have been
described for purposes of this disclosure, numerous changes and
modifications will be apparent to those of ordinary skill in the art.
Such changes and modifications are encompassed within the invention as
defined by the claims.